The feedback I have from people having Amd64 processors is that you only have 4 Linux distro's doing the job: Debian, (k)ubuntu, Fedora and Gentoo. From those four, Debian an (K)ubuntu are the ones with a good packages support for that arch. Now, to choose between Debian or (K)ubuntu is up to you, since the decision left isn't arch-dependant anymore.

I'm partial and I'll say Gentoo (Linux) ;) being involved in both Gentoo KDE and Gentoo AMD64 works, I find it suits me well... or I suit it, whatever :PGentoo/FreeBSD mainly doesn't support anything but x86 right now (need to find time to complete the work on amd64 port).

I would also have to say Gentoo, but I am biased as I am a developer for Gentoo and most of my systems are amd64. I have an X2 processor that works great, and I am not aware of any multilib issues we have. I have a couple of workstations (one X2), a Turion based laptop and a web server all running amd64 Gentoo Linux.

My reasons: 1. source based-ness makes it less likely that packages haven't been "built" for the arch. 2. gentoo forums are a good resource for the less common problems that can crop up with a less mainstream arch. 3. these new machines are fast enough to make compiling everythin not so bad ;-)

I don't have a suggestion for which distro, but I highly encourage you to buy from a Linux-friendly vendor, one that sells computers with Linux pre-installed. That way you don't have to worry about getting a W$ refund.

Here's a list of vendors selling desktops and workstations pre-intalled with GNU/Linux:

Another Gentoo vote. I used to use slackware (and still do on my laptop), but since I bought an intel 64 processor I installed gentoo.The "hard" work was the one afternoon I used to install and configure the system. While doing that I learn everything about gentoo there was to learn (for a user I suppose). Sinds then I've been updating the system once a week. Or like today because I know kde 3.5.1 has been released. Rock solid, all the packages I need (student, so things like latex, kile, java, vpn, etc... just have to work). And a good x86 mode to fall back, like when to install flash and things like that.As an added bonus, while this is an 64 bit system, it is not amd, so I was able to optimize it specific for my processor. This is no problem for you, but yeah, it counts.

Kubuntu.I've noticed lots of Gentoo votes. As an ex-Gentoo user, I can say that it's not worth it. You must compile just about everything you install, and for VERY little benefit and much disappointment.Here's a list of the pluses and the minuses of both.Kubuntu has an installer, Gentoo doesn't (except for one in alpha version)Gentoo makes it easier to make your system exactly fit your hardwareKubuntu works out of the boxGentoo has a few more packages than Kubuntu in its repositoriesKubuntu and Ubuntu are identical except for WM's, and therefore any app compiled to work in Ubuntu works in Kubuntu.Kubuntu uses .debsAnd finally, Kubuntu automates SO much more. Gentoo requires CONSTANT attention.

I vote Gentoo also, I've never had a better linux experience than when I've been running Gentoo. Sure, it may not automate away absolutely everything, but it does what you need it to, and allows you to have the system YOU want rather than the system the packagers have given you.

I've used kubuntu, but the problem I find is that I always want something that isn't available in the maintained packages. Then, you have to search for other apt repositories.. then when you add it (which is not easy btw) and try to install, then you run into dependency problems. Try compiling anything from source? Well, have fun adding all of the *-dev packages.

Gentoo has a SINGLE, centralized repository, so dependency hell is virtually gone. Even if not, compiling and installing something manually (which you WILL do in linux) requires no extra work.

I'll be the lone weirdo here... I'm running an AMD Athlon 64 3200+ with SuSE 10.0.Overall I've been very happy, but lately I've been getting frustrated at the lack of quickly updated packages. Also, it defaults to putting 32bit libs in /lib/ and 64bit in /lib64/ which seems to throw some things off, looking for primary libs in the 32bit dir, not realizing there's another dir to explore.Let's hear some more arguments for (k)ubuntu! I'm curious about it!

I'd vote for Fedora. It has quite a lot of support behind it, an organized development scheme and for (at least) the last 2 revisions was a fully-capable x86_64 distro: they build everything they can for x86_64 and also provide i386 packages of things like OpenOffice. You can also freely grab i386 packages from the neighbouring i386-based release of Fedora Core. Gentoo is "source-based"? So is Fedora. Just get the SRPMs and rebuild your own RPMs right on your machine.

I don't know about gentoo, but ubuntu is fast enough for me and has almost same packages for amd64 than for i386. Furthermore there is a very interesting entry at ubuntuformums.org about how to setup a 32bit chroot (eventhough most of 32bit software runs out of the box).

I've been running my personal workstation at home on an AMD64 box with Suse. I installed 9.3 about 18 months ago from a boxed set. Went without a hitch. I later seamlessly upgraded to a downloaded version of 10.0.

I have two more systems running MythTV on Fedora Core 4 on AMD64 hardware. These run the MythTV application well; but the installation and updating is more a little more work. In addition I've experienced problems with X86_64 and 386 library dependency conflicts.

I've read above one comment stating that "Gentoo is gerally considered to have the best amd64 support."

I've researched comparisons on the web and the very few I've found lean to Ubuntu and Debian, so I'd say the above statement is probably unique to the Gentoo community, and not at all true of the Linux community at large.

That being said, I've used both 5.10 and 6.06, Ubuntu and Kubuntu, on my skt 754 athlon 64 3700+ in a DFI mobo with hitachi sata hdd, nec dual-layer dvd burner, asus combo drive, multi-card reader, ati x700 graphics and 1G corsair ram flawlessly for over a year now. It has been stable as a rock. multimedia support has been no problem. All KDE apps work fine. Java has worked fine. The only exception has been flash, but there is a way around that installing minimal 32-bit support libs from existing repos without having to chroot (even though that is an obvious option). The support forums are outstanding. There's a reason this distro has garnered so much attention, even being so much younger than Gentoo.

To address one other complaint about KUbuntu in these replies, there is absolutely no truth to the statement that adding repositories is difficult in KUbuntu. The fact is, it is no more difficult that adding repositories to any debian-based distro. This statement shows a lack of very basic knowledge and experience with apt-get.

Also, just like other debian-based distros, if it's not in the repos, you can likely find and download the pre-compiled app you want, and use dpkg -i (for .deb) or alien (for rpm, suse, etc.) to install.